1. Field of the Invention
The present invention relates to an improved method of monopolymerizing or copolymerizing vinyl chloride, and more particularly a method of preventing the polymer from adhering to the inner wall surface of a polymerization tank and the like at the time of polymerization. Further, the present invention also relates to a coating agent for preventing a polymer from adhering to the inner wall surface of a polymerization tank and the like and to a method of producing said coating agent.
2. Prior Art
Vinyl chloride is polymerized alone or copolymerized (hereinafter simply referred to as "polymerized") with a monomer copolymerizable with it. However, the polymer adheres to apparatus parts that are in contact with the monomer(s) during the polymerization such as a polymerization tank inner wall, reflux condenser, stirring blades, baffles, and various attached pipeline connecting parts, there arise such problems that the cooling capability of the polymerization tank decreases or the polymer adheres to the apparatus parts and then break off to go into the homopolymer or copolymer (hereinafter referred to as "product") of vinyl chloride thereby lowering the quality of the product. Therefore, customarily, every time after the completion of polymerization, the inside of the polymerization tank is cleaned and then polymerization is effected, but to do so needs much labor and time, which leads to the reduction of the operating efficiency of the polymerization tank and the increase of the production costs.
Accordingly, hitherto, techniques have been suggested wherein an agent is applied to the inner wall of a polymerization tank and other parts to prevent a polymer from adhering thereto.
However, although these techniques are effective for preventing a polymer from adhering, they are accompanied by such defects that the polymerization rate is lowered and physical properties of the product are deteriorated and therefore they are not satisfactory to be used industrially. Further, although techniques that do not influence adversely the polymerization rate and physical properties of the product are suggested, the techniques are not so much effective for preventing a polymer from adhering. For example, although techniques wherein a co-condensate of resorcin and an aldehyde is applied (JP-A ("JP-A" means unexamined published Japanese patent application) Nos. 502169/1982 and 502170/1982) are suggested, the effect for preventing a polymer from adhering is still not adequate.